Bravo XR Drive Rebuild

Matt · 04 October 2021, 08:27

Some of you might remember I was looking for a replacement Bravo XR upper a few weeks back. Couldn't find anything "interesting", so instead just ordered all the tools and parts to rebuild mine.

Note quite finished yet - am waiting for an imperial dial gauge & extension to arrive so I can measure the driven gear backlash. A metric dial gauge doesn't fit. (25.4 is not the answer).

Anyway - getting there. The bravo gearbox really is an excellent piece of design.

Jon Tallis · 04 October 2021, 11:22

Ok...now we're having workshop envy [emoji4]

Matt · 04 October 2021, 16:24

It's just a sheet of 19mm ply 8x4 bolted the wall with some screws in. Makes it all look tidy though doesn't it keeping all the tools hung up. It's the only successful way I've ever found of keeping all my tools fairly well organised.

paulbrown22 · 04 October 2021, 18:18

And then the tool chests, engine hoist, welder, compressor, etc. :-)

Very nice workshop, and great work on the Bravo drive. I rebuilt the transom shield, swivel pin and tiller arm assemblies on mine with uprated components soon after buying the Ribtec, but hadn't yet opened up the leg assembly. Having sadly now sold it, now I will never have that fun with that boat at least!

Matt · 04 October 2021, 18:53

It’s a lifetime of being disappointed most times I’ve paid someone else to do a job for me, with only a very few exceptions. So my default response is to spend the money on tools to do the jobs myself. That’s not to say I don’t sometimes get it not quite right too, but it does mean I know who to blame when something breaks.

paulbrown22 · 04 October 2021, 19:21

Completely agreed - I'm much the same, and have no problem buying decent tools if it means I can then do most things myself. Still need to improve the workshop to come up to your standard though!

Matt · 04 October 2021, 19:44

Very kind, thank you.

That mig is the newest addition actually. It’s proper, british made, Oxford welding.
And I’ll be disappointed if it lasts less than 20 or 30 years.

willk · 05 October 2021, 07:23

A fascinating subject. We should have more Workbench Wonders threads....

Matt · 05 October 2021, 07:58

So I ordered a Mitutoyo imperial gauge and extension to measure the backlash from a company who listed them as in stock. Aside from not getting any order confirmation from them, when I called them they shared that "in stock" doesn't necessarily mean in the UK - it could be in one of their other offices in the world!!! Fortunately Ireland has one - but they quote 7 working days from ireland to the UK and then onwards to me.

"In Stock". FFS.

Anyway, it'll be nice to have a mitutoyo dial gauge - but I'd quite like to get the drive back together too.

So have also ordered one of these, which as it's extra long, should do the job. It has the right imperial stem diameter too
Hopefully here thursday: https://www.machine-dro.co.uk/0-2-in...ndicator-gauge

willk · 05 October 2021, 12:23

Quote:

Originally Posted by Matt

Fortunately Ireland has one - but they quote 7 working days from ireland to the UK and then onwards to me.

"In Stock". FFS.

"That's an EU export mate *sucks teeth* - more than my job's worth to guess delivery dates!"

If it's any consolation, Screwup Screwfix are getting your own back on us!

jwalker · 05 October 2021, 16:34

Quote:

Originally Posted by Matt

So I ordered a Mitutoyo imperial gauge and extension to measure the backlash from a company who listed them as in stock. Aside from not getting any order confirmation from them, when I called them they shared that "in stock" doesn't necessarily mean in the UK - it could be in one of their other offices in the world!!! Fortunately Ireland has one - but they quote 7 working days from ireland to the UK and then onwards to me.

"In Stock". FFS.

Anyway, it'll be nice to have a mitutoyo dial gauge - but I'd quite like to get the drive back together too.

So have also ordered one of these, which as it's extra long, should do the job. It has the right imperial stem diameter too
Hopefully here thursday: https://www.machine-dro.co.uk/0-2-in...ndicator-gauge

That's a mahoosive DTI Matt!
I know you said you're needing an imperial DTI but given that 1 thou is about 3.9 hundredths of a mm you'll likely get better accuracy with a metric DTI. Doesn't the end of your DTI screw out so you can fit an extension?

And, you didn't show us all the knackered bits!

Matt · 05 October 2021, 18:22

It's been a learning curve on the nuances of all the different DTIs, for sure.

Generally, metric ones have an 8mm shank, whereas imperial ones have a 3/8 shank. In addition, the metric ones have 2.5mm thread on the tip, whereas the imperial ones have a 4-48UNF thread.

The mitutoyo imperial stuff with a 2" extension fits the mercury indicator mount just right. The giant one is also just right.

I had a hunt round in the stores and have found a metric extension...but then also managed to unearth a linear tools imperial gauge - but with a metric thread and an 8mm shank too...

So in short....I'll be ending up with more dial gauges than a chap could ever need and probably want.

And at the end of it, the answer I want is 12 thou.

Matt · 05 October 2021, 18:27

Slightly rusty bits, caused by a very slight leak in the top o-ring.
Not enough for the oil level to drop or see a leak, but enough to let a sniff of moisture in....

So I also have a pressure tester now too..

jwalker · 05 October 2021, 19:59

Quote:

Originally Posted by Matt

....Generally, metric ones have an 8mm shank, whereas imperial ones have a 3/8 shank. In addition, the metric ones have 2.5mm thread on the tip, whereas the imperial ones have a 4-48UNF thread....

He he...well your next machine needs to be a lathe so you can make adaptors so everything can be made to fit everything else!

How did you know there was drive failure, first indications, noise, lack of drive etc.?

Matt · 05 October 2021, 20:15

Got one. But it’s a bit worn, so the next job should really be adjusting and shimming that.

Anyway, symptom was I could hear the bearings whining when I ran it up on the hose. Pulled the top cap and then saw the bearing condition.

jwalker · 05 October 2021, 20:53

OK, a noise to listen out for. Forearmed....

Matt · 05 October 2021, 22:30

1. 12 Thou Backlash. That's what we wanted.
2. And then you have to reset the pinion gear preload - sneak it off a bit with the press and then reset the preload to 10 in-lbs of drag on the bearings.
3. Almost looks like a drive again. Gearshift linkage to do and we might be there.

Matt · 05 October 2021, 22:33

You won't miss it: https://1drv.ms/v/s!AhLMmfVtRmsDkcku...__e1g?e=421Xin

Quote:

Originally Posted by jwalker

OK, a noise to listen out for. Forearmed....

Matt · 06 October 2021, 10:08

P.S. JW that last pic of the drive on the stand didn't come out particularly well - but I included it since I recall your boat runs an outdrive - albeit a volvo not a merc - and I thought the stand might be interesting

It's an engine stand frame with a adjustable heavy duty caravan jackstand welded onto a bracket, with a pair of beams on it for the drive to sit on.

As a combination of a tool for fitting the drive to the boat, moving the drive around, storing it, and giving me a stable platform to be able to work on the drive, it's been an absolute gamechanger.

Only thing I would change is that if it was a permanent drive stand, I'd make it slightly narrower, it's a bit wide really - but when I have the engine on the stand instead of the drive, I want all that width - so it stays like this.

Matt · 06 October 2021, 18:42

Pressure test passed - 15psi for half an hour.
Time to reinstall and go boating. Just in time for summer.